Methane blast triggers tunnel collapse at NHPC project in Sikkim; multiple workers trapped, rescue hampered by toxic fumes

A major rescue operation is underway in Sikkim after a methane gas explosion triggered a landslide inside the under-construction NHPC Teesta Stage-VI tunnel project, trapping several workers deep inside the tunnel.

According to preliminary reports, methane gas had accumulated around 1.5 kilometres inside the tunnel. Around midday, an attempt to release the trapped gas reportedly triggered an explosion, leading to a landslide that blocked a section of the tunnel.

At least 17 workers are believed to have been trapped in the incident. While some workers managed to escape on their own, several others remain stranded inside, including a worker reportedly from Jholungay in the Samardung area of South Sikkim.

Initial rescue efforts by the Rangpo Fire and Emergency Services were unsuccessful after personnel encountered dangerously low oxygen levels and toxic gas inside the tunnel. Some rescuers reportedly fell ill due to inhaling the fumes and had to retreat.

A subsequent rescue attempt by the National Disaster Response Force (NDRF) also failed to reach the trapped workers because of the hazardous conditions inside the tunnel.

Senior district officials and disaster response teams remain stationed at the site, with rescue operations continuing under extremely challenging conditions. Authorities are exploring ways to improve ventilation and stabilise the affected section of the tunnel before attempting another rescue.

As of the latest reports, no trapped worker has been brought out, and officials have not yet released an official statement on casualties or the exact number of people still inside the tunnel.

The incident marks one of the most serious accidents at the NHPC Teesta Stage-VI hydropower project, with rescue teams racing against time amid unstable tunnel conditions and high methane concentrations. Authorities are expected to provide further updates as the operation progresses.